Cutter for dredges



Jan. 25, 1944. F. A. GILL 2,340,216

CUTTER FOR DREDGES Filed May 27, 1941 s Sheets-Sheet i $12 35 lNVENTOR 3M a. BY

@MQMM ATTO R N EY Jan. 25, 1944. F. A. GILL 2,340,216

CUTTER-FOR DREDGES Filed May 27, 1941 5 Sheets-Sheet 2 INVENTOR 1 14 a.W m Mir;

ATTORNEY Jan. 25,1944. F A G" 2,340,216

CUTTER FOR DREDGES Filed May 27, 1941 3 Sheets-Sheet. 3

ay/3 gay/4 INVENTOR ATTORNEY Patented Jan. 25, 1944 CUTTER FOR DREDGESFred A. Gill, Lebanon, Pa., assignor of one-half to Guy W. Sackett,Christiansburg, Va.

Application May 27, 1941, No. 395,337

3 Claims. (01.37-67) The invention relates to cutters for suctiondredges and more particularly to cutters of the type disclosed inSackett Patent No. 1,226,386, dated May 15, 1917.

The present invention constitutes an improvement over the cutterdisclosed in the above-mentioned Sackett patent, although its principlesare not necessarily limited to cutters of the Sackett type. The Sackettcutter comprises a cutter head generally in the shape of a crowncomprising a rim or base at one end and a nose or hub at the other endunited by curved helical-like blades, the edges of which constitutecutting edges. Se-= cured to these blades are sockets in whicharelocated cutting teeth for enhancing the cutting effect of the blades,particularly when working, on harder materials, such as hard pan,coral,,soft rock, etc. While the Sackett cutter has gone into extensivecommercial use, its cutting teeth are subject to considerable wear,necessitating frequent sharpening and replacement.

The present invention providesa cutter which not only increases thespeedof cutting but. also greatly increases the life 'of the cutter headand cutter teeth, increasing the length of. the periods betweensharpenings and greatly increasing the overall life of the cutter teeth.According" to the present invention, the 'teeth are madetmore slender,increasing the length of their cutting edges and providing a positiverelief or clearance along the depth or width of the tooth which providesmore of a cutting or splitting action and reduces friction and wear onthe teeth.

The teeth, as shown in the Sackett patent and as heretofore used, are inthe nature of picks and are made comparatively thick and heavy andprovide points which do most of the cutting ac-' tion. These teeth aresubject to considerable wear because they shatter and break the rockrather than split or cleave it.

The invention also provides for the bending of nd .shift, some or all ofthe teeth being bent,;

in the cutter in use. 7 1

The present invention also locates the, teethon.

if necessary, in accordance with the results noted that the teeth onsuccessive blades do not trail each other. w The invention also consistsin certain'ne'wan'd original features of construction and combinationsof parts hereinafter set forth and claimed.' Although the novel featureswhich are believed to be characteristic of this invention will be par;ticularly pointed out in the claims appended hereto, the inventionitself, as to its objects and advantages, and the manner in which itmaybe carried out, may be better understood by refer ring to the followingdescription taken in connece tion with the accompanying drawings forming a part thereof, in which 7 V Fig. 1 illustrates a common form ofdredg'eof which the invention is applied. Fig. 2 is an end view of thecutter head looking; axially thereof, teeth being shown in some of thesockets and omitted in others for purposes of illustration. t

Fig. 3 is a side elevation with parts broken away of the new cutterhead, some of the teeth being omitted.

theseveralcutter blades in staggered relation so 66;

. Fig. 4 is a side elevation of a new tooth acc ording to the invention.7 t

Fig. 5 is a top plan View of the tooth inFig. 4. Fig. 6 is an endelevation of the tooth looking, from nose toward the shank of the tooth.I, Fig. 7 is a section on the line 7-1 of Fig, 4 throughthe blade of thetooth. Fig. 8 is a section on the line 88 of Fig.4- through the shank ofthe tooth. Figs. 9 and 10 are side elevations of the tooth,corresponding to Fig. 4, showing the blade bent upwardly and downwardlyrespectively with re-,- spect to the shank. f Figs. 11 and 12 are topplan views of the tooth. corresponding to Fig. 5, but showing theblade-of the tooth bent to the right and to the left respectively withrespect to its shank looking from shank to nose. a 1, Figs. 13 and 14are semi-diagrammatic views, looking axially of the cutter andillustrating the, bending of the tooth blades downwardly and upwardlyrespectively, and 4 Figs. 15 and 16 are semi-diagrammatic side;elevations of a cutter illustrating the blades of,- the tooth bent tothe right and leftrespectively, as viewed in these figures. j, g In thefollowing description and in theclaims, various details will beidentified by specific names; for convenience, but they are intended tobeas; generic in their application as the art will permit; Likereference charactersdenote like partsin the several figures of thedrawings,

In the drawings accompanying and forming part of this specification,certain specific disclosure of the invention is made for purposes ofexplanation, but it will be understood that the details may be modifiedin various respects without departure from the broad aspect of theinvention.

Referring now to the drawings and more particularly to Fig. 1, myinvention is shown applied to one form of suction dredge, this figureshowing the parts somewhat diagrammatically. The water or stream isdenoted by H and the bed or deposit it is desired to remove is indicatedby l2. The barge or float upon which the dredging apparatus is mountedis denoted by H). The cutter denoted by 13 is driven by drive shaft. I4which in turn is driven by a suitable prime mover H in such manner thatthe shaft 14 may have universal movement with respect to the dredge Ill.The suction pipe l5 extends from a point within the cutter l3 and hassuitable universal connection with suitable pumping apparatus located onthe dredge lil. The drive shaft M and suction pipe l5 are assembledtogether and provided with a suitable means for permitting a workman toclimb out to the cutter 13 when it is raised out of the water. Thisassembly indicated by I6 is commonly known as a ladder and this laddertogether with the cutter l3 is movable both vertical-1y and horizontallyby a suitable derrick including tackle l9 and beams l8 as will beunderstood by those skilled in the art.

Referring now to Figs. 2 and 3 the cutter 13 comprises a head or spiderconnected to drive shaft M which is suitablyjournaled in a cutter headbearing 22 suspended from a link 2i con-- nected to the tackle or ladderfall [9. The bearing 22 has a bearing surface 23 for supporting the rimor back ring 24 of the spider 28. The spider 20 has a hub 25 to whichshaft M is suitably secured. Hub 25 and rim 24 are connected by Warpedblades 26 which are connected or braced by circular rods or braces 21 tolimit the si-zeo'f the openings between the exterior and interior of thehead 29. The bearing 22 alsosupports the lower end of suction pipe l5which'has an opening 3| communicating with the interior of the head 20.

The blades 26 have sharp cutting edges 28 on the sides facing in thedirection of rotation, i. e their leading edges are sharp, and areprovided with sockets 29 to receive the teeth 30 which are suitablykeyed thereto.

The blades 26 extend generally helically from the central hub 25,in adirection opposite to the direction of rotation of the head indicated byAin Fig. 2, to the rim or base 24 of the crownshape'd cutter head 26.Every other blade 26 hassixteeth while the intermediate bladeshave fiveteeth, the teeth on alternate blades being staggered axially of thecutter so thattheteeth onth'e irr'in'iediately following blades donotfollow directlyi'n the paths cut by the teeth immediately preceding.-As in the Sackett patent, the blades 26 are shaped to provide a nose Mprojectingaaxially of the hub 25 and to insure there being always somepart of some blade in cutting action.

Referring now to Figs. '4 to 8, the teeth 30. are made up of a taperedshank 32 having topsurface 33, bottom surface 34 and sidesurfaces 35 and36, this shank-engaging a similarly shaped interior surface of theseveral'sockets 29. Integral with the shank 32 is a blade 311 having atop-surface 38 and converging side surfaces 33 and 40 forming.relief'angles c (Fig. "7) The intersection of top surface 38 and sidesurfaces 39 and 40 form cutting edges 42 for which the relief angles 0are provided. The side faces 39 and 40 meet in a comparatively narrowbottom edge 01' surface indicated by as which partakes or" a gentlecurve from the nose 4! merging into the bottom surface 34 of shank 32.The blade 31 and shank 32 are joined by a portion indicated by 46 whichwill be termed the neck, at which the blade may be bent with respect tothe shank 32 for certain purposes as will hereinafter be described morein detail.

The approximately median line through the shank and blades of a straighttooth will be called the axis for convenience and is indicated by -45.When the teeth are mounted in their sockets this line or axis is locatedin a plane substantially perpendicular to the axis of rotation for teethnear the rim 24, while the sockets for those teeth nearer the nose Mlocate the axes of the teeth at increasingly greater angles with rwpectto planes perpendicular to the axis of revolution as indicatedparticularly in Fig. 3. In all cases the tooth axes are located atpositions between radii from the axis of rotation passing through theteeth and tangents to said radii, which indicate the direction of toothmove ment at any particular instant. Thus. the top surface 38 andcutting edges d2 of the tooth blades 31 are leading surfaces and edgeswhile the bottom edges G3 are trailing.

Before explaining the useof the invention some idea of size will begiven. It will be understood that we are dealing with heavy machinery.For example, the cutter head may weigh about 15,000 lbs. and eachindividual tooth may weigh between and lbs. In the particularinstallation illustrated, there are 33 teeth so the teeth alone willweigh consider-ably over a ton. The cutter head may be five or six feetin diameter at its rim or open end and may be five or six feet inlength, that is, axially. The cutter .teeth may run over two feet inlength and may be 4 inches wide at the top and 4 inches in depth (fromtop 38 to bottom 43). The cutter head may rotate at a speed of 20revolutions per minute. It will be understood that the above figures areillustrative only and the various sizes, weights and other values willvary with the particular installation.

To use the above invention, new and sharp straight teeth 30 havingsubstantially the shape indicated will. be mounted in the cutter headsockets 29: and keyed or locked in. The cutter head l3 will of coursehave been detached from drive shaftv 14, the work of mounting the teeth30 being done on the deck of barge I-ll as will be understood by thoseskilled in the art. Thehead or spider 20 will then be mounted inposition on the end of the-driveshaft M, the ladder 16.0fcourse, beingin raised position to permit this operation. Theladder will then belowered into the water and we, are ready for dredging.

The dredging procedure will .depend upon the technique of the particularoperator and also upon conditions or the nature of the bed to. be,removed. The dredge Willbe moved to plac the cutter head I3up'againstthe bed it. is desiredft'o. cut illustrated-by- I2 in'Fig. 1,'thecutter'headwill be started rotating-in the di-rection indicated by thearrow -A'in Fig. 2 and the ladder f6 will be moved in a long horizontalsweep, cutting in the direction indicated by the arrow B. At theend ofeach horizontal sweep, the ladder i6 willbe returned no cutting beingdone'on thereturn trip.

'Upon the'next cuttin'gitrip in the direction'oi the arrow B, a furtherline or path will'be cut'in the rock l2. edges 28 wi1l cut the softermaterials such as clay, etc. The teeth 30 will cleave the rock intocomparatively small pieces which must pass through the openings in thecutter head whence they are sucked by the suction pipe l5 and dischargedin accordance with well-known suction dredge practice. I

After a given cutting period, which again will depend upon cuttingconditions but which may be three or four hours, the ladder I6 israised, the cutter stopped and a man crawls out on the ladder to look atthe teeth. If the teeth are not too dull, the cutting may be resumeduntil it is decided that the teeth are too dull for further work.

...While the cutting operation is going on, a spare cutting head will beconditioned to replace the cutting head in use when it must be removedafter becoming dull. The cutting teeth will be mounted in the spare head20in a manner sim-' ilar to mounting them on the first head, but some orall of the new teeth, or resharpened teeth, as the case may be, insteadof all being straight, will be bent to overcome the wear as indicatedby. an

inspection of the teeth on the first head. Thus,"

when the first head must be removed for further sharpening of its teeth,the spare head will be ready to be put in place. The length of a-cuttingperiod will vary with conditions, running for 6X? ample from 18 to 20hours. For hard rock,-.the period may be as short as '12'hours beforethe head must come off for the resharpening ofthe teeth. For soft rock,the period may be as long as 48 hours before it is necessary to removethe head for resharpening. v

For bending the teeth a special bending press may be provided. Thebodies of the teeth will be bent at their necks 46 with respect to theirshanks 32, either up as in Fig. 9; down as in Fig. 10; right as in Fig.11; or left as in Fig. 12, considering the surfaces 33 and 38 as the topof the tooth andlooking from shank 32 to nose 4|. Generally speaking,the side bending will be in the direction of wear. For example, if atooth in use shows more wear on the right side (surface 39) the corresponding tooth of the spare job will be bent toward the right side tothe shape shown in Fig. 11. If the wear is on the left side (surface 40)the. corresponding tooth will be bent toward the left side to the shapeshown in Fig. 12. The up and down-bending will be dependent upon theamount of wear on the lower edge 43 of the teeth. If the wear on loweredge 43 is too great, indicated by the depth or width (distance fromupper surface 38 to lower edge 43) being too small, generally speaking,the tooth will be bent downwardly as indicated in Fig. 10; if the wearon lower edge 43 is too little, the tooth will be bent upwardly as shownin Fig. 9.

The relationship of the teeth with respect to the axis of rotationindicated by 41 and the effect of bending will be better understood byreferring to Figs. 13-16. Here the sockets are omitted to betterillustrate the tooth angles. In Fig. 13 the tooth blade 31 is bent withrespect to its original axis 45 downwardly, or oppositely to thedirection of rotation A, through the angle d, thus corresponding to Fig.10. In Fig. 14 the tooth blade 31 is bent upwardly, or into thedirection of rotation A, through the angle e, corresponding to Fig. 9.In Fig. 15 the tooth blade is bent laterally toward the rim 24 throughangle 1, corresponding to Fig. 12. In Fig. 16 the tooth blade Thecutting blades 26 having cutting,

is bent laterally. toward the nose 44 through angleg, corresponding toFig. 11. V

The uneven distribution of wear on the several teeth is caused byanumber of factors, among whichare the kind and condition of the deposit,the direction of .stratification, etc. In any event, whatever. thecauseofuneven wear on the several teeth, the teeth .are bent eithersideways or up and downto'lessen this wear so that, when the sparecutter head is placed in cutting position, it will cut more efficientlyand its teeth will last longeni When the first cutting head is removedfrom its drive shaft, itsteeth are removed and they are sharpened .by;.heating and. pounding undera steam hammerto-replace the cutting edges 42and to provide the relief 0 as indicated in Fig. 7; The sharpening.orhamme'ring action draws the teeth, using'the stock .in the body toform the cutting edges and the relief angle similarto the originalteeth, but as the tooth. is repeatedly sharpened, thev blade 31 becomesthinner, although its cuttingedgesand relief angles will be keptconstant;- As the teeth become thinner, they naturallybe'commore'efiicient in their cutting or, splitting action. As an example, anaverage tooth may-take four or five sharpenings before it must bediscarded, .but the use of the invention will double the tooth lifebetween sharpenings.

The tooth according to the invention is highly efficient in that. itprovides more efficient cutting or splitting action and less pulverizingor ham! mering, action The comparatively thin blade 31 providessplitting efiiciency and the depth or width of the, blade providessufficient strength" to permitthe blade to be narrow and the reliefangle 0 ,orzclearance reduces friction and resist-' ance of the teeth asthey pass through the rock. The repeated scraping of the rock on theteeth: acts as abrasive which gradually Wears the teethaway, but thenarrower teeth acting as blades, become more'emcient in use due to theincreased splittingaction. The tapering of the upper sur-: face 38 ofthe tooth blade and the more uniform thicknesspof thelower edge43provides a variable relief angle c; increasing from nose 4| to shank- 32It will be found that thebending of the teeth not only increasesthe lifeof the teeth but also increases the life ofthe sockets 29. It 'is customary tov replace the metal scraped from the sockets by the abrasion ofthe rock, by adding metal by welding. Th bending of the teeth protectsthese sockets and reduces the. amount of the material it is necessary toadd to the sockets.

Thus, a cutting tooth for suction dredges is provided which has highercutting efliciency and longer life. The relief angle reduces thefriction of the teeth as they pass through the rock. The narrowness ofthe teeth makes it more bladelike and its depth gives it strength. Thebending of the teeth reduces uneven wear by causing the teeth to biteinto the rock rather than to merely scrape it. A scraping tooth does nocutting and yet adds friction and wears out prematurely.

While certain novel features of the invention have been disclosedherein, and are pointed out in the annexed claims, it will be understoodthat tier sockets of generai-lyrectangular ternal cross section, teethin said sockets, each tooth having a relatively heavy tapered shank ofgenerally rectangular cross section seated in its socket and a cuttingand "wedging blade comparatively deep .or wide in the direction orcutting movement and comparatively thin in the direction transverse tovsaid cutting movement, said tooth blade having a com-nanatime-ly flatleading surface merging into the top surztace of said shank, saidleading surtace eonveming in width outwardly to a blunt nose ofrestricted dimension, said tooth blade having side surfaces convergingto a relatively small blunt trailing edge, the intersection of saidleading surface and said side surfaces fanning edges, said convergingside surfaces providing relief for said cutting edges, said trailingedge merging the bottom surface of said shank, said trailing edgeextending from shank to nose andior'ming :a relatively small angle withsaid leading surface near said shank and for .a substantial part oflength of the blade, and partaking or anrdtuberant outline toward theouter end vof the blade and f-orming a relatively large acute angle withsaid leading surface at said nose, the general tapering nature of saidtooth blade from shank to hose providing wedging action as the toothenters the rock, the comparatively thin and deep or wide blade and itsrelieved cutting edges iproviding cutting action as the tooth :cuts .aswath through the rock.

.2. In hydraulic suction dredging, a rotary cutter having sockets ofgenerally rectangular in: ternal cross section, teeth in said .sochets,each tooth having a relatively heavy tapered shank of generallyrectangular cross section seated in its socket and a cutting and wedgingblade comparatively deep or wide in the direction of cutting movementand comparatively thin in "the direction. transverse to said cuttingmovement, said vidin-g relief for said cutting edges, said reliefbecoming increasingly larger from said-nose toward said shank, saidtrailing edge 'being substantially coextensive with the adjacentbottomsin-race of said shank, said trailing edge extermiing from to noseand donning a relativel small angle with said leading surface near shankandror-a substantial part or length of the blade; and partaking of aprotuberant outline toward the outer end of the blade and form'- ing arelatively large acute angle with said leadingsurface at said nose, thegeneral tapering nature of said tooth blade fromshan-k to noseprovidingwedging action as the tooth enters the rock, the comparativelythin and deep or wide blade and its relieved cutting gesprovidms cuttingaction as the tooth cuts a swath through therock. l

'3, In hydraulicgsuction dredging, a rotary cut.- ter. comprising. acrown-shaped head having a hub and a :back ring, a plurality ofhelicoidal blades connecting said hub and {back ring, .sockets ofgenerally rectangular internal ,crcssesece tion on said blades, teeth insaid sockets, each tooth having a relatively heavy tapered shank ofgenerally rectangu ar cross section seated in its sockets and a cuttingand wedgi-ng blade comparatively deep or wide in the direction ofcutting movement and comparatively thin in the direction transverse "tosaid cut-ting movement said tooth blade having a comparatively flatleading surface substantially coextensive with the adjacent top surf-aceof said shank, said leading surface converging in width outwardly to ablunt nosenose of substantial but restricted dimension, said :toolihblade ihaving side surfaces converging to a relatively small hlunttrailing edge, the inters'ection of said lea-ding surface and said sidesmifaces forming cutting edges, said converging side surfaces providingrelief for said cutting edges, said relief becoming increasingly lar erfrom .said nose toward said shank, rsazld'trailing edge beingsubstantially coextensive the adiacent bottom surface of said shank,said .trailing edge extending from shan'kto nose and describing .arelatively small angle with said leading surface near said shank and fora substantial of length or the blade, and describing a gentle curvletoward the outer end of the blade ending in :a relatively large :acuteangle with said leading surface atisaidnose, the general tapering natureof said tooth blade from shank to mose providing wedging action as thetooth enters the rock, the 'wmpamtively and deep .01 wide blade and itsrelieved cutting edges providing cutting action as the tooth cuts aswath through therock;

FRED A. GILL.

